Electric motor control system



June 30, 1942. c. H. WILLIS 2,288,339

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Inventor:

Clodius H. Willis by W 6 HIS Attorney.

June 30, 1942. 1

c. H. WILLIS ELECTRIC MOTOR CONTROL SYSTEM Original Filed Oct. 27, 19373 Sheets-Sheet 3 FigiO.

Inventor:- Clodius HWHIis,

His Attorney.

Patented June 30, 1942 H 2,288,339 ELECTRIC Moron oorz'raor. SYSTEMClodius H.

General Electric Company,

New York Willis, Princeton, N. J., assignor to a corporation 01'Original application October 2'7, 1937, Serial No. i

171,354. Divided and this application December 23, 1938, Serial No.247,494

13 Claims. (Cl. 17223 9) 'My invention relates to electric controlsystems and more particularly to electric valve circuits for controllingelectric motors.

This application is a division of my copending application Serial No.171,354 concernin electric motor control systems, filed October 27,1937, and assigned to the assignee of the present application.

In the control of dynamo-electric machines, such as motors of the directcurrent type, it is important to provide control systems which permitgreat flexibility in the control of an output characteristic, such asthe speed thereof, without sacrificing efficiency of operation andeconomy of apparatus. In accordance with the teachings of my inventiondescribed hereinafter, I provide new and improved circuits, such aselectric valve rectifying circuits, which may be employed forcontrolling an operating characteristic, such as the speed, of a directcurrent motor.

It is an object of my invention to provide a new and improved electriccontrol system.

It is another object of my invention to provide a new and improvedelectric control system for electric motors.

It is a further object of my invention to provide new and improvedelectric valve circuits for controlling electric motors.

It is a still further object of my invention to provide new and improvedcontrol systems for direct current motors whereby there is affordedgreat flexibility in speed control, and in which the size and rating ofthe auxiliary control apparatus are of suitable proportions and economyrelative to the size of the motors to be controlled.

In accordance with illustrated embodiments of my invention, I provide animproved control circuit for energizing a direct current motor from analternating current circuit through electric valve apparatus, wherebythere is provided a great flexibility of control. paratus interposedbetween the alternating current circuit and the armature circuit of thedirect current motor is of the full wave type, one half of the electricvalves being of the controlled type having control members forcontrolling the conductivities thereof, and the other half of theelectric valves being of the uncontrolled type. The energization of thearmature circuit, and hence the speed of the direct current motor, arecontrolled by controlling the phase of the alternating voltagesimpressed on the control members of the controlled electric valves. Theexcitation circuit of the direct current motor is en- Electric valveapergized from an electrical neutral connection provided by anelectrical network energized from the alternating current circuit andfrom a potential of the uncontrolled electric valves, so that theenergization of the excitation circuit is derived irom a unidirectionalsource of substantially constant voltage. Current controlling means areconnected in the excitation circuit to control the energization thereof.

For a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanyingdrawings, and its scope will be pointed out in the appended claims. Fig.1 represents an embodiment of my invention as applied to an electricvalve control system for a direct current motor in which a full waveelectric valve apparatus is connected between a polyphase alternatingcurrent circuit and the armature circuit of an induction motor. One halfof the electric valves are of the controlled type and the other half areof the uncontrolled type. The controlled electric valves are providedwith control members and the variation in speed of the direct currentmotor is effected by controlling the energization of the control membersof the electric valves. The field or excitation circuit of the directcurrent motor is energized in accordance with the voltage appearingbetween an electrical neutral connection established by an associatedelectrical network and a. potential of the uncontrolled electric valves.Figs. 2 to 9, inclusive, represent certain operating characteristicsrelating to the arrangement shown in Fig. 1. Fig. 10 represents a stillfurther embodiment of my invention in which the speed of an inductionmotor is controlled by an electric valve circuit and in which anarrangement is provided for simultaneously controlling the energizationof the excitation circuit of an associated direct current motor, and forcontrolling the conductivity of the electric valve apparatus. Fig. 11 isa modification of the arrangement shown in Fig. 10 as applied to thecontrol of a direct current motor.

Fig. 1 illustrates an embodiment of my invention as applied to anelectric valve system for energizing a direct current motor from analternating current circuit. The direct current motor I6 is energizedfrom an alternating current circuit 52 through electric valvetranslating apparatus 63 which may be of the full-wave type. One half ofthe electic valves are of the uncontrolled type and the other half areof the controlled type having control members for controlling the con-The electric valve appaductivities thereof.

connected electric valves 64-65, 66-61, and 6869 preferably of the typeemploying an ionizable. medium such as a new a vapor. The electricvalves 64, 66 and 68 are of the uncontrolled type and each comprises ananode I and may include cathodes II. It is to be understood that thecathodes 1| may be of the filamentary type or may be of the pool type.When the cathodes II are of the D001 type, the electric valves may alsoinclude a pair of holding anodes I2. The holding anodes I2 maintainelectric valves 64, 66 and 68 conductive continuously during positivehalf cycles of applied voltage. Each of the electric valves 65, 61, and69 includes an anode I8, a pair of cathodes I4, and a control member I5.I provide an excitation current I6 for impressing on control members Iof electric valves 65, 61, and 69 suitable periodic voltages, such asalternating voltages, to render valves 65, 61, and 69 and hence controlsthe voltage impressed on armature II of motor I6.

I provide an electrical network 80 comprising a plurality of windings 8|and 82 and associated secondary windings 83. "The network 60 alsoaffords an electrical neutral connected 84 which is connected to oneterminal of field winding I8 through a current controlling device suchas a variable resistance 65. The other terminal of field winding I8 isconnected to the common juncture of electric valves 64, 66, and 68, thatis, connected to the anodes I0 of these valves. In this manner there isimpressed across the terminals of the field winding I8 a substantiallyconstant unidirectional voltage. The control of the energization of theexcitation circuit for machine I6 may be effected by adiustment of thevariable resistance 85. One terminal of the armature I! of motor I6 isconnected to the anodes of the uncontrolled electric valves 64, 66,

Thecurves of Figs. 2 and 3 may be referred, -to in explaining theoperation of the embodiassociated supply circuit 62 and a reduction inthe current obtained from the supply circuit.

Fig. 4 shows the direct current output voltage as a function of gridvoltage retardation where all the electric valves of a full-waverectifier are phase controlled, and Fig. 5 represents the output voltageas a function of the grid voltage retardation where only half theelectric valves are phase controlled. It will be notedthat in the lowervoltage region the output voltage is extended to a greater range byemploying phase I shift in only one-half of the electric valves.

ment of my invention shown in Fig. 1. .More

specifically, the curves of Fig. 2 show the mannor in which electricvalves conduct current when a full-wave rectifier is employed and whenall of the elect-tic valves of the group are phase controlled. Thecurves of Fig. 3 illustrate the operation when only one-half of theelectric valves are phase controlled in the manner shown by thearrangement of Fig. 1. The principal trolled rectifier.

electric valves 64, 66, and 68 are not controlled.

This feature makes it possible to dispense with the need for anauxiliary source of direct current for energizing a fieldwinding anddispenses with the necessity of auxiliary rectifying apparatus where asource of direct current is not available.

Fig. 10 represents another embodiment of my invention as related to anelectric valve system for controlling an induction motor in which adirect current motor. is energized through electric valve means andreturns power to the rotating member of theinduction motor. tric valveapparatus '63 may be of the type in which only one-half of the electricvalves are phase controlled, as shown in Fig. 10, or may be of the typein which all of the electric valves are phase controlled.

In order to control conjointly the conductivity of electric valvetranslating apparatus 63 and the energization of the excitation circuitfor direct current motor I6, I provide a control circuit I05 comprisingan excitation circuit I06 for controlling ,the conductivity oftheelectricvalve translating apparatus 63, and a suitable currentcontrolling device such as a rheostat I0'I which is connected in circuitwith field winding I8 of machine I6. The excitation circuit I06comprises a transformer having primary windings I08 and secondarywindings I09 which impress suitable periodic voltages, such asalternating voltages, on

' control members I5 of electric valves 65, 61, and

69. A suitable source of negative biasing potential, such as a batteryIIO, may be employed and current limiting resistances III may beconnected in series relation with control members I5. A

suitable phase shifting arrangement, such. as a rotary phase shifterII2, may be connected to excitation circuit I06 to provide anarrangement for controlling the phase of the periodic voltages impressedon control members .15. The current controlling means I01 may comprise aresistance H3 and an actuating member H4. The actuating member H4 isarranged to produce simul taneous control of the energization of windingI8 of machine I6 and control of the phase of the periodic voltagesimpressed on control members I5. One way in which this simultaneous orjoint control may be effected is by the employment of a shaft II5 whichinterconnectsthe actuating The elecseries with field winding I8.

member I and the rotary phase shifter H2. The current controlling means"l1 and the excitation circuit I 06 may be arranged to control thetransfer of power from induced windings 3 to machine IS in threedistinct ways within-the various ranges of speed. One way in which thistype of speed control may be effected is by design of the resistance H3,so that within the lower range of speed control the transfer of powerbetween induced-windings 3 and machine I is effected primarily .by thephase control of the electric valves. The upper portion of resistance H3is arranged so that for a predetermined displacement of the actuatingmember M4 the energization of the field winding I8 is not varied. For anintermediate speed range, the control of the transfer of power betweenwindings 3 and machine 16 is eifected by the conjoint control of theexcitation of machine and the control of the conductivities of theelectric valves. Within the upper range of speed control, the transferof power between windings 3 and machine 15 is effected primarily bycontrolling the excitation of machine l6 by controlling the resistancein A suitable gear mechanism H5 may be employed to obtain the desired,angular displacements of the rotary phase shifter H2 in accordance withadjustment of the actuating member H4.

The excitation circuit I06 may be energized from any suitable source ofalternating current correlated in phase and frequency relative to thevoltage of the induced winding 3 of machine I, and is shown as beingconnected to the induced winding 3. A suitable phase shiftingarrangement, such as a rotary phase shifter I I], is interposed betweenthe induced winding 3 and the excitation circuit 106 to permitadjustment of the phase of the periodic voltages impressed on controlmembers 75 of electric valves 55, 61, and 69. An operating condition,such as the speed of induction motor i, maybe controlled by causing thedirect current motor I6 to absorb variable amounts of power from theinduced winding 3 through the electric valve apparatus 63. The speed ofinduction motor I may be controlled by the adjustment of the actuatingmember H4, which controls the energization of field winding I8 ofmachine it and controls the conductivities of electric valves 65, 61,and 69. For the position of the actuating member Ill shown in Fig. 19,the speed of the induction motor! will be minimum. The speed of theinduction motor I may be increased by rotating the actuating member H4in a counter-clockwise direction of rotation. At the minimum speedvalue, the field excitation of machine is is maximum and the armaturevoltage of machine 16 is zero. Within the first range of speed control,the field resistance is maintained substantially constant and the speedis increased by increasing the voltage impressed on armature ll ofmachine l6 due to the advance in phase of the voltages impressed oncontrol members 15. Within the intermediate range of speed control, theexcitation of machine l6 and 6 During this last range of speed control,the'voltage impressed on armature I1 of machine It is substantiallyconstant. The operating characteristics shown in Fig. 5 may be referredto in explaining the eflect of the control of the conductivities ofelectric valves 65, 61 and 69 with respect to these ranges of speedcontrol. Within the first range of speed control, the voltages impressedon control members I5 are advanced in phase from approximately the onehundred degree position to the fifty degree position; within the secondor intermediate range of speed control voltages impressed on controlmembers 15 are advanced in phase from the flity degree position to zeroposition; and within the third or upper speed range, the .voltages areadvanced in phase beyond the zero position. By this arrangement it isclear that the conjoint control of the excitation of machine l6 and thecontrol or the armature voltage may be effected without employingapparatus which is complicated in construction and operation. The rotaryphase shifter H1 may be adjusted to control independently the speed ofthe motor I and the power factor at which power is transmitted frominduced windings 3. In this manner, the power factor of the inductionmotor I may be controlled independently.

In Fig. 11 of the accompanying drawings there is diagrammaticallyillustrated a modification of the arrangement shown in,Fig.. 10 asapplied to an electric valve circuit for controlling the speed of adirect current motor. Many of the elements of the arrangement shown inFig. 11 are similar to those shown in Fig. 10 and corresponding elementshave been assigned like reference numerals. The armature ll of the motorHi is connected to be energized from the alternating current circuit 4through electric valves 64-68. Electric valves 64, $5 and 68 are of theuncontrolled type and electric valves 65, 51 and 69 are of thecontrolled type which control the voltage impressed in armature ll.

As an agency for controlling the conductivities ofelectric valves 65, 61and 69 and as an arrangement for providing an electrical neutralconnection for field winding l8 of machine 15, I provide a phase shifterH8 having primary windings I I9 and secondary windings I20. Primarywindings H9 are connected to provide an electrical neutral connection|2l which is connected to one terminal of field winding l8 through thecontroller M1. The other terminal of the field winding I8 is connectedto the armature l1 and the common juncture of the uncontrolled electricvalves 64, 66 and 58. Secondary windings I20 of phase shifter H8 impressalternating voltages on control members 15 of electric valves 65, 81 and$9.

The operation of the arrangement shown in Fig. 11 is 'substai'itiallythe same as that explained above in connection with the control systemof Fig. 10. Briefly, the speed of the direct current motor 15 iscontrolled by variation in the voltage applied to the armature I! and bycontrol of the energization of the field winding IS. The controller 10'!and the phase shifter H8 second or intermediate range of speed controlis obtained by the conjoint variation in the excitation of machine Itand by the variation of armature voltage; and in the third or upper Thatis, in the first or tion, and I, therefore, aim in the appended,

claims to cover all such changes and modifications as fall within thetrue spirit and scope of my invention.

What I claim as new" and desire. to secure by Letters Patent ofthe'United States, is:

1. In combination, a source of alternating current, a dynamo-electricmachine of the direct.

current type including armature and excitation circuits, an electricalnetwork connected to said alternating current circuit and having anelectrical neutral connection, electric translating apparatus connectedbetween saidalternating current circuit and said armature circuit andcomprising a pair of serially connected electric valves, only one of.said electric valves being provided with a control member forcontrolling the conductivity thereof, saidexcitation circuit beingconnected to be energized in accordance with the voltage appearingbetween the other of said electric valves and said neutral connection,and

means for energizing said control member to control an electricalcharacteristic of said ma.- chine.

2. In combination, a polyphase alternating current circuit, adynamo-electric machine of the direct current type having armature andexcitation circuits, an electrical network connected to said alternatingcurrent circuit and'having an electrical neutral connection, electrictranslating apparatus connected between said alternating currentcircuitand the armature circuit and comprising a plurality of pairs of seriallyconnected electric valves, said pairs of electric valves. beingconnected across the armature circuit, one

electric valve in each of said pairs of electric valves being providedwith a control member for controlling the conductivity thereof and theother valve in each pair being of the uncontrolled type, the excitationcircuit being connected to be energized in accordance with theunidirectional voltage appearing between said neutral connection and theuncontrolled electric valves, and means for energizing the controlmembers to control an electrical characteristic of said machine.

3. In combination, a polyphase alternating current circuit, anelectrical network energized from said circuit and having a neutralconnection, a dynamo-electric machine of the direct current type havingarmature and excitation circuits, a plurality of pairs of seriallyconnected electric valves connected between said alternating currentcircuit and the armature circuit, said pairs of electric valves beingconnected across said armature circuit andeach pair of electric valvesincluding one controlled electric valve' having a control member forcontrolling the conductivity thereof and the other valve in each pairbeing of the uncontrolled type, one terminal of said excitation circuitbeing connected to said neutral connection and the other terminal ofsaid excitation circuit being connected to the uncontrolled electricvalves in said pairs of valves, and means for energizing the control 1rality of pairs of serially connected'electric valves,

members to control an electrical characteristic of said machine.

4. In combination, a polyphase alternating current circuit, adynamo-electric machine of the direct current type having armature andexcitation circuits, electric translating apparatus connected betweensaid alternating current circuit and the armature circuit and comprisinga plueach pair of electric valves comprising a controlled electric valveand an uncontrolled electric valve, the common juncture of thecontrolled electric valves being connected to one terminal of thearmature circuit and the common juncture of the uncontrolled electricvalves being connected to the other terminal or the armature circuit,and an electrical network connected to said alternating current circuitand having an electrical neutral connection, the excitation circuitof-said machine being connected between said neutral connection and thecommon juncture of the uncontrolled electric valves.

5. In combination, a polyphase alternating current circuit, .adynamo-electric machine of the direct current type having armature andexcitation circuits, electric translating apparatus I connected betweensaid alternating current circuit and the armature circuit and comprisinga plurality of pairs of serially connected electric valves, each pair ofelectric valves comprising a controlled electric valve and anuncontrolled electric valve, the common juncture of the controlledelectric valves being connected to one terminal of the armature circuitand the common juncture of the uncontrolled electric valves beingconnected to the other terminal of the armature circuit, an electricalnetwork connected to said alternating current circuit and having anelectrical neutral connection, the excitation circuit of said machinebeing connected between said neutral connection and the common junctureof the uncontrolled electric valves, and means for controlling theenergization 0! said excitation circuit.

6. In combination, a polyphase alternating current circuit, adynamo-electric machine of the direct current type including armatureand excitation circuits, electric translating apparatus connectedbetween said alternating current circuit and said machine and comprisinga plurality of pairs of serially connected electric valves, each of saidpairs including an uncontrolled electric valve and a controlled electricvalve having a control member for controlling the conductivity thereof,the common juncture of said uncontrolled electric valves being connectedto one terminal of the armature circuit and the common juncture of thecontrolled electric valves being connected to the other terminal of thearmature circuit, an electrical network connected to said alternatingcurrent circuit and having an electrical neutral connection, oneterminal of the excitation circuit being connected to said neutralconnection and the other terminal being connected to the common junctureof the uncontrolled electric valves, means for con-' tion, electrictranslating apparatus connected to said sourcev and comprising a pair ofserially connected electric valves, only one of said electric valvesbeing provided with a control member for controlling theconductivitythereof, a direct current circuit connected to said electricvalves,

means for energizing said control member to control an electricalcondition of said direct current circuit, and a second direct currentcircuit energized in accordance with the voltage appearing between theother of said electric valves and said neutral connection.

8. In combination, a source of alternating current, electric translatingapparatus connected to said source and comprising a serially connecteduncontrolled electric valve and a controlled electric valve having acontrol member for controlling the conductivity thereof, an electricalnetwork connected to said source and having an eleccurrent, a directcurrent circuit, electric translating apparatus connected to said sourceand comprising a serially-connected uncontrolled electric valve and acontrolled electric valve having a control member for controlling theconductivity thereof, said electric valves each having a holding anode,said direct current circuit being connected across saidserially-connected electric valves, an electrical network connected to,said source and having an electrical neutral connection and winding forenergizing the holding anodes, and a second direct current circuitconnected to be energized in accordance with the unidirectional voltageappearing between said uncontrolled electric valve and said neutralconnection.

10. In combination, a source of alternating current, a direct currentcircuit, electric translating apparatus connected to said source andcomprising a serially-connected uncontrolled electric valve and acontrolled electric valve. havmg a control member for controlling theconductivity thereof, said electric valves each having a holding anode,said direct current circuit being connected across saidserially-connected electric valves, an electrical network connected tosaid source and having an electrical neutral connection and windings forenergizing said holding anodes, a second direct current circuit 55connected to be energized in accordance with the unidirectional voltageappearing between said uncontrolled electric valve and said neutralconnection; and means for energizing the control member to controlan'electrical condition of said first mentioned direct current circuit.

11 In combination, an alternating current circuit, a direct currentmotorhaving armature and excitation circuits, electric translating apparatusconnected between said alternating current circuit and the armaturecircuit and comprising a serially-connected uncontrolled electric valveand a controlled electric valve having a control member for controllingthe conductivity thereof, and a phase shifting circuit for impressing onsaid control member a periodic voltage variable in phase to control thevoltage impressed on the armature circuit and including an electricalnetworklconnected to said alternating current circuit having anelectrical neutral connection, said excitation circuit being connectedbetween the uncontrolled electric valve and said neutral connection.

12. In combination, an alternating current circuit, a direct currentmotor having armature and excitation circuits, electric translatingapparatus connected between said alternating current circuit and thearmature circuit and com prising 'a serially-connected uncontrolledelectric valve and a controlled electric valve having a control memberfor controlling the conductivity thereof, a phase shifting device forimpressing on said control member a periodic voltage to control thevoltage impressed on the armature circuit and including an inductivenetwork connected to said alternating current circuit having anelectrical neutral connection, said excitation circuit being connectedbetween the uncontrolled electric valve and said neutral connection, andmeans for conjointly controlling said phase shiftmg device and theenergization of said excitation circuit.

13. In combination, an alternating current circuit, a dynamo-electricmachine having an armature winding and a control winding. electrictranslating apparatus connected between said circuit and said windingand comprising means for rectifying both half cycles of voltage of saidalternating current circuit including-a pair of electric valves only oneof which is of the type having a control member for controlling thecurrent transmitted to said winding, means for energizing said controlwinding at constant voltage from said electric translating apparatus,and means {or impressing a voltage on said control member to control thecurrent conducted by said electric valve means to energize variably saidarmature winding.

- CLODIUS H. WILLIS.

CERTIFICATE OF CORRECTION Patent No. 2,288,559. June 0, 1 m.

CLODIUS H. WILLIS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 17, for "current" read --circuit; and line 59, for"resistance 95" read --resistance 85; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this 11th day of August, A. D. l9LL2.

Henry Van Arsdele, (Seal) Acting Uommi ssloner of Patents.

CERTIFICATE OF CORRECTION.

latent No. 2,288,559. June 50, 19L' 2.

CLODIUS H. WILLIS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 17, for "current" read --circuit--; and line 59, for"resistance 95" read --resistance 85--; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this 11th day of August, A. D. l9L 2.

Henry Van Arsdale, (Seol) Acting commissioner of Patents.

